A61M5/31576—Constructional features or modes of drive mechanisms for piston rods

A61M5/31578—Constructional features or modes of drive mechanisms for piston rods based on axial translation, i.e. components directly operatively associated and axially moved with plunger rod

A61M5/3158—Constructional features or modes of drive mechanisms for piston rods based on axial translation, i.e. components directly operatively associated and axially moved with plunger rod performed by axially moving actuator operated by user, e.g. an injection button

A—HUMAN NECESSITIES

A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE

A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR

A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests

A61M5/178—Syringes

A61M5/31—Details

A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms

A61M5/31533—Dosing mechanisms, i.e. setting a dose

A61M5/31545—Setting modes for dosing

A61M5/31548—Mechanically operated dose setting member

A61M5/3155—Mechanically operated dose setting member by rotational movement of dose setting member, e.g. during setting or filling of a syringe

A61M5/31551—Mechanically operated dose setting member by rotational movement of dose setting member, e.g. during setting or filling of a syringe including axial movement of dose setting member

A—HUMAN NECESSITIES

A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE

A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR

A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests

A61M5/50—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests having means for preventing re-use, or for indicating if defective, used, tampered with or unsterile

A—HUMAN NECESSITIES

A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE

A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR

A61M2205/00—General characteristics of the apparatus

A61M2205/58—Means for facilitating use, e.g. by people with impaired vision

A61M2205/582—Means for facilitating use, e.g. by people with impaired vision by tactile feedback

A—HUMAN NECESSITIES

A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE

A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR

A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests

A61M5/178—Syringes

A61M5/31—Details

A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms

A61M5/31525—Dosing

A—HUMAN NECESSITIES

A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE

A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR

A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests

A61M5/178—Syringes

A61M5/31—Details

A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms

A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR

A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests

A61M5/178—Syringes

A61M5/31—Details

A61M5/32—Needles; Details of needles pertaining to their connection with syringe or hub; Accessories for bringing the needle into, or holding the needle on, the body; Devices for protection of needles

A61M5/3202—Devices for protection of the needle before use, e.g. caps

Description

The invention relates to cylinder ampoules of the type comprising a tubular vessel having a
first end with a membrane sealingly closing this first end, and a second end closed by a piston
which can be forced into the tube to press out a liquid, e.g. a medicine, stored in said
tube between said piston and the membrane when an injection needle is mounted piercing
the membrane.

This type of ampoules or cartridges are used in various types of syringes and manual or
automatic medication apparatuses. The syringes may either be of a durable type where the
user changes the ampoule when it is empty or they may be disposable in which case the
ampoule is mounted in the syringe by the manufacturing and the whole device inclusive the
ampoule is disposed of when the ampoule is empty. In automatic medication apparatuses
the ampoule may be changed when it is empty or it may be a part of a disposable part comprising
parts of the apparatus which has to be changed frequently, e.g. infusion needle,
catheter, batteries etc. This way it is ensured that these parts are changed at least each time
a new ampoule has to be mounted.

In pen shaped syringes it is desirable that the piston in the ampoule is blocked against
backward movement when it has been pressed forward in the ampoule to press out a dose
of medicine through a needle mounted at the neck end of the ampoule. Immediately after an
injection is made by pressing home an injection button and the pressure exerted on an injection
button is released an internal pressure exist in the ampoule due to the elasticity of the
piston and the flow resistance in the needle. This pressure is settled when the liquid has
passed out through the needle and is absorbed in the tissue, but if the pressure on the injection
button is released before such an absorption is finished the pressure in the ampoule will
press the piston backward to settle this pressure and the full set dose will not be injected.

Blocking of the piston against such backward movement is commonly obtained by providing
a piston rod, through which the pressure is transmitted from the injection button to the piston,
with teeth which are engaged by a pawl provided in the housing of the syringe. EP 327 910
describes a syringe for insulin injection by which the teeth on the piston rod each has a
length corresponding to the distance the piston has to be advanced to obtain the injection of
the minimal dose which can be set. I.e. the blocking of the piston against movement in a
backward direction takes place in steps. A continuously acting blocking is obtained in the syringe
described in WO 92/12747 wherein the blocking is performed by a sharp edged leaf
spring which is mounted in the syringe housing and engages a smooth piston rod at an acute
angle so that the piston rod may be passed forward to press the piston into the ampoule
whereas an attempt to pass the piston rod backward will make the sharp edges of the leaf
spring cut into the piston rod to stop further backward movement. If this analogue detent
mechanism is used in syringes of the durable type the cutting marks which the leaf spring
makes in the piston rod will soon make this piston rod appear rather as a toothed than a
smooth rod.

An ampoule according to the preamble of claim 1
is known from WO 90/004424.

It is an object of the invention to provide an ampoule of the kind described in the opening of
this application and by which the detent blocking the piston against backward movement is
attached to the disposable ampoule instead of relying on parts of the injection mechanism of
the syringe.

This is obtained by an ampoule of the kind mentioned which is according to the invention
characterised in that the ampoule tube is made from a plastically deformable material and
the spring plate may be made of a harder material than is the ampoule,
preferably from an elastic metal.

The parts of the spring plate abutting the inner wall of the ampoule may due to the direction
of their deflection slide over the wall when the piston is pressed inward in the ampoule. If the
piston attempts to move outward in the ampoule, the abutting edges of the ampoule wall will
cut into this wall an stop any outward movement of the piston. The cut marks left by the cutting
edges of the spring plate are made in the wall of the ampoule which will in all cases be
disposed of when the ampoule is empty. Consequently the cut marks will not be detrimental
to the function of a new ampoule which replaces the used one. As the retraction detent is
always positioned immediately behind the piston a minimal tolerance chain is obtained as
the influence of the elasticity of the piston rod will not be added to the influence of the elasticity
of the piston.

In an embodiment of the cylinder ampoule according to the invention the spring plate may be
integral with the pressure foot. Further the piston rod may be integral with the pressure foot
so that the piston, the spring plate, the pressure foot, and the piston rod forms an integral
unit.

In another embodiment of the invention the spring plate is a rectangular leaf spring plate
extending through a slot in the pressure foot and having diagonals which are longer that the
inner diameter of the ampoule. The corners of the plate at the ends of the diagonals are deflected
away from the piston towards the open end of the ampoule to form an acute angle
with the ampoule wall when the pressure foot is pressed into the end of the ampoule to abut
the piston. This construction allow the pressure foot to be moved inward in the ampoule by
which movement the deflected corners will slide over the wall whereas an attempt to move
the pressure foot outward will make the corners of the leaf spring plate bite into the wall of
the ampoule to block any outward movement of the pressure foot.

Another object of the invention is to provide a rotation detent which prevents rotation relative
to the ampoule. Such a rotation detent may be obtained by splitting up the spring plate so
that the engagement between this plate and the ampoule wall takes place in a number of
circumferentially spaced points or zones of the ampoule wall. When the plate cuts into the
ampoule wall in such spaced zones the engaging parts of the plate have to force their ways
through the parts of the ampoule wall separating the points or zones of engagement if the
plate shall be rotated. This will yield a considerable resistance against rotational movement
of the plate relative to the ampoule and elements coupled to the plate in a way preventing
relative rotation of these elements and the plate will also be prevented from rotation relative
to the ampoule.

Further according to the invention the ampoule may have an extension extending beyond
the piston when the ampoule is full. This extension may surround the piston rod over the entire
length of this rod.

The piston rod may be provided with an outer thread and the full ampoule may be extended
behind the piston to surround the piston rod over its entire length. Provided with these features
the ampoule may form a main part of a pen shaped syringe further comprising dose
setting and injection means cooperating with the piston rod and a cap covering at least a
part of the ampoule and its extension. Such a syringe can be disposed of when the ampoule
is empty.

According to an embodiment of the invention the extension of the ampoule may on its inner
wall provided with a protrusion which cooperate with the with dose setting and injection
means to provide an auditive and tactile indication of the setting of a dose and a stop defining
the maximum dose which can be set.

Further according to an embodiment of the invention the extension at the transition from the
ampoule to said extension is along its perimeter provided with equidistant axial recesses engaged
by an axial spline at the inner wall of the cap to block against relative rotation of the
ampoule and the cap during the operation of the dose setting member. By this construction
the ampoule is rotationally fixed in the cap and rotatiing the dose setting setting means relative
to the cap means rotating the dose setting means relative to the ampoule and the piston
rod.

According to still another embodiment of the cylinder ampoule according to the invention and
end edge of the extension is provided with a toothing comprising teeth having a abrupt leading
edge and a ramp shaped training edge, which toothing co-operates with a corresponding
toothing on an edge of a dose setting and injection button. By said toothings the dose setting
and injection button it is ensured that the dose setting and injection button from its zero
point can only be rotated in a direction by which a positive dose is set.

According to an embodiment of the cap fits over the ampoule and its extension and may
abut the dose setting and the injection button, and the cap may have a recess in its abutting
edge and a scale along this edge and the injection button has on its abutting edge a projection
fitting into the recess in the injection button. When the cap is mounte with protrusion on
the dose setting and injection button engaging the recess of the cap it is ensured that a
marker on said protrusion points at the zero on a scale on the outer perimeter of the cap.

In the following the invention will be described in further details with references to the drawing,
wherein

Figure 1

shows a sectional view of a cylinder ampoule according to the invention with a
detent mechanism allowing only unidirectional movement of the piston,

Figure 2

shows a top view of the ampoule in figure 1,

Figure 3

shows a sectional view of a disposable syringe based on an embodiment of
the cylinder ampoule according to the invention.

Figure 4

shows a cross section along the line IV-IV in figure 3, and

Figure 5

shows a cross section view along the line V-V in figure 3,

Figure 6

shows a perspective view of a detail of the syringe in figure 3.

Figure 7

shows a detail of the syringe in figure 3,

Figure 8

shows a partly sectional view of the syringe in figure 3 seen in the direction
indicated by line VIII - VIII in figure 4,

Figure 9

shows a part comprising a nut member and a press button and a connecting
tubular element,

Figure 10

shows in enlarged scale a detail comprising the nut member in figure 9.

In figure 1 a cylinder ampoule 1 has end provided with a neck 2 which is at its outer end
provided with a flange 3 against which a rubber membrane 4 is sealingly held by a metal
cap 5 having an edge gripping behind the flange 3. The metal cap 5 forms a needle hub receiving
part onto which a hub 6 carrying a double ended needle 7 is mounted with an end
piercing the rubber membrane 4 and communicating with the inner space 8 of the ampoule
1.

The other end of the cylinder ampoule 1 is closed by a rubber piston 9 which is at its side
turning away from the inner space 8 of the ampoule 1 backed up by a foot 10. The foot 10 is
provided with a detent metal leaf spring plate 11 which is secured to the piston 9 in a slot.
The metal leaf spring plate 11 is as it is seen in figure 2 provided with protrusions 12 engaging
corresponding recesses in the foot 10 to ensure that the leaf spring plate11 is not drawn
out of the slot.

Such ampoules are mainly made from glass but the invention is based on the fact that the
ampoule is made from a somewhat softer plastically deformable material into which the
edges of a leaf spring may cut, e.g. a suitable plastic. The leaf spring is made from an elastic
material which can cut into the plastic of the ampoule, e.g. metal or a hard plastic.

The piston 9 is backed up by a pressure foot 10 through which a pressure is transmitted to
the piston 9 by a piston rod in the device wherein the ampoule is used. In the shown embodiment
the leaf spring plate 11 is formed as a rectangular elastic plate having diagonals
which are slightly larger than the inner diameter of the ampoule so that the corners of the
plate is deflected backward, i. e. away from the piston 9, when the foot 10 with the leaf
spring plate 11 is pressed into the ampoule. Thereby the deflected corners form an acute
angle with the inner wall of the ampoule 1 so that said corners may slide over said wall when
the foot 10 with the leaf spring plate 11 is pressed inwards in the ampoule but will cut into
said wall if an attempt is made to move the foot 10 with the leaf spring plate 11 outward towards
the open end of the ampoule 1.

Figure 3 shows a disposable pen shaped syringe which is based on a special embodiment of
an ampoule according to the invention in which embodiment a threaded piston rod 13 is integral
with the foot 10 and the ampoule 1 has an extension 14 extending beyond the outermost
position of the piston 9 to form a tube surrounding the piston rod 13. The syringe works
according to the principles known from the syringe described in EP 327 910 where a dose is
set by screwing a nut along a threaded piston rod to lift a button connected to the nut away
from a stop, and where the set dose is injected by pressing the button home to abutment
with the stop. In the following the syringe according to figure 3 will be further described the
elements already known from figure 1 being allocated the same reference numbers as in figure
1.

An ampoule 1 has at its open end an extension 14. The piston 9 closing the open end of the
ampoule 1 is provided with a foot 10 carrying a piston rod 13 which has an outer thread 15.
A leaf spring plate 11 is mounted in a slot through the foot 10 to allow only inward movement
of said foot and the piston 9 in the ampoule 1 as the corners of the spring plate 11 cut into
the walls of the ampoule 1 which is made from e.g. plastic. As the corners of the leaf spring
plate 11 cuts into the ampoule walls also rotation about the longitudinal axis of the ampoule
is blocked so that a piston rod guide like those which are commonly used to make a piston
rod inrotatable relative to the housing can be omitted. The ampoule 1 with its extension 14
forms the housing of the syringe and only a dose setting and injection member and a protecting
cap 16 has to be added. The cap is 16 is tubular and fits over the ampoule 1 and its
extension 14. The dose setting and injection means comprise a nut member 17, a button 18,
and a tubular member 19 connecting the button 18 and the nut member 17. The nut member
17 has an internal thread and is mounted with this internal thread engaging the outer
thread 15 of the piston rod 13. The tubular member 19 runs inside the extension 14 coaxial
with this extension and connects the nut member 17 to the button 18 which lies outside the
extension 14 but in abutment with the end of this extension 14. The abutting edges of the
extension 14 and the button 18 are provided with engaging toothings which have teeth, 20
and 21 respectively, with ramp shaped leading edges and an abrupt trailing edges as shown
in figure 6. These toothings ensure that the button can from its abutment position only be
rotated in the direction by which the button is lifted away from the extension and not in the
direction by which the piston is drawn outward in the ampoule.

The button 18 has an outer diameter corresponding to the outer diameter of the cap 16 and
he outer cylindrical wall of the button 18 flush with the outer cylindrical wall of the cap 16
when this cap is mounted on the ampoule 1 with its edge abutting against an outer edge 24
of the button. As shown in figure 7 a projection 25 on this outer edge 24 must engage a recess
32 in the edge of the cap 16 to obtain said abutment. This way it is ensured that the
cap 16 is always mounted with its recess 32 opposite the projection 25. The projection is
provided with a pointer 26 pointing at a scale along the edge of the cap 16. This scale has its
zero at said recess so that the pointer 26 will point at zero on the scale when the cap is
mounted.

The extended ampoule is at the transition between the very ampoule 1 and the extension 14
provided with a number of longitudinal recesses 22 distributed equidistantly along the perimeter
of the ampoule. A protrusion 23 on the inner wall of the tubular cap 16 engages one
of the recesses 22 to block rotation of the cap relative to the ampoule.

When a dose is going to be set, the cap 16 is displaced axially to bring the projection 25 out
of engagement with the recess 32 in the edge of the cap 16. The projection and the recess
may have sloping edges so that the projection 25 automatically slides out of the recess 32
and push the button 18 and the cap 16 away from each other when it is attempted to rotate
the button and the cap relative to each other. It shall be noticed that such rotation may only
be made in one direction due to the engaging toothings on the cap and the button. The dose
is set by this rotation of the button relative to the cap and the size of the dose may be read
on the scale along the edge of the cap 16. Due to the fact that the cap due to the engagement
of the recesses 22 and the protrusion 23 is inrotatable relative to the ampoule and that
the piston rod due to the spring plate 11 biting into the ampoule wall is inrotatable relative to
the ampoule, the nut member is rotated relative to the piston rod 13 when the cap 16 and the
button 18 is rotated relative to each other. The allowed direction of rotation is chosen so that
the nut will move up along the piston rod and lift the button 18 up from the edge of the extension
14 of the ampoule 1 as shown in figure 6.

As one revolution of the button will make the pointer 26 point at zero again, marks 27 on the
tubular member 19 may indicate the numbers of revolution of the button 18 so that the doses
corresponding to the full revolutions can be added to the dose shown on the scale.

The outer side of the nut member 17 is along it's perimeter provided with a number of equidistant
recesses 29 corresponding to the number of positions on the scale, and a tooth
shaped protrusion 30 on the inner wall of the extension 14 of the ampoule 1 enables a releasable
locking of the nut member 17 relative to the ampoule at each position of the pointer
26 relative to the scale. The locking is obtained by the protrusion 30 engaging one of the
recesses 29 and the unlocking is obtained when said protrusion during further rotation is
pressed out of the recess against the resilience of the extension to engage the next recess.
By this locking mechanism an audible and tactile indication of the dose setting is obtained.

When the nut member is screwed up along the piston rod, this movement is stopped when
an annual outer flange 28 on the nut member 17 abuts the tooth shaped protrusion 30 on
the inner wall of the extension of the ampoule. The abutting surface of the protrusion 30 is
shaped with an abrupt leading edge and a ramp shaped trailing edge to form a tooth which
engages corresponding teeth 33, shown in figure 10, on the abutting surface of the flange
28. By this precaution the stopping is obtained by mutual abutment of abrupt leading edges
of a pair of teeth and is this way made well defined. Another stop is provided by an end
plate 31 at the end of the piston rod 13. The thread of the nut member cannot pass this end
plate and this way it is ensured that a set dose does not exceed the volume remaining in the
ampoule.

Claims (11)

A cylinder ampoule comprising a tubular vessel (1) having a first and a second end, a
membrane (5) sealingly closing said first end, and a piston (9) closing said second end
which piston can be forced into the tubular vessel (1) to press out a liquid, e. g. medicine,
stored in said vessel (1) between a first end of said piston (9) and said membrane (5)
through an injection needle (7) piercing the membrane (5), a pressure foot on which a piston rod is acting (10) and a spring
plate (11) are provided, the pressure foot (11) abutting a second end of the piston (9) and
the spring plate (11) being carried by the pressure foot (10) and being mainly perpendicular
to the longitudinal axis of the ampoule and having at least one diameter which is larger
than the inner diameter of the ampoule so that edges of the plate abutting the inner wall of
the ampoule are deflected away from the piston (9) to form an acute angle with said wall,
characterised in that the ampoule tube being made from
a plastically deformable material
and that the spring plate (11) is made from a harder material than is the ampoule.

A cylinder ampoule according to claim 1, characterised in that the spring plate (11) is
made from an elastic metal.

A cylinder ampoule according to claim 1, or 2, characterised in that the spring plate (11)
is integral with the pressure foot (10).

A cylinder ampoule according to claim 1, or 2, characterised in that the spring plate is a
rectangular leaf spring plate and that the pressure foot (10) has a slot perpendicular to the
longitudinal direction of the ampoule through which slot the spring plate (11) extends
having diagonals which are longer that the inner diameter of the ampoule.

A cylinder ampoule according to anyone of the preceding claims, characterised in that
the spring plate (11) is split up to engage the ampoulewall in a number of circuferentially
spaced points or zones.

A cylinder ampoule according to anyone of the preceding claims, characterised in that a
piston rod (13) is provided which piston rod is integral with the pressure foot (10) and projects
in the longitudinal direction of the ampoule away from the piston (9).

A cylinder ampoule according to claim 6, characterised in that it forms a part of a pen
shaped syringe wherein a dose setting and injection means (17, 18, 19) is provided
which is carried by the piston rod (13), the piston rod being provided with an outer thread
(15) engaging an inner thread in a nut member (17) forming a part of the dose setting
and injection means.

Cylinder ampoule according to claim 7, characterised in that it is on its inner wall provided
with a protrusion (30) which can cooperate with longitudinal recesses (29) in the nut
member (17) of the dose setting and injection means to provide an auditive and tactile indication
of the setting of a dose and with a stop defining the maximum dose which can be
set.

A cylinder ampoule according to claim 8 characterized in that along its perimeter the
ampoule provided with equidistant axial recesses (22) which can be engaged by an axial
spline (23) at the inner wall of a cap (16) covering at least a part of the ampoule to block
against relative rotation of the ampoule and the cap during the operation of the dose setting
member (17, 18, 19).

Cylinder ampoule according to claim anyone of the claims 7 to 9, characterised in that
an end edge of the ampoule is provided with a toothing comprising teeth (20) having a
abrupt leading edge and a ramp shaped training edge, which toothing cooperates with a
corresponding toothing on an edge of a dose setting and injection button (18)

Cylinder ampoule according to claim 10, characterised in that the cap fits over the
ampoule and abuts the setting and injection button, and that the cap has a recess in its
abutting edge and a scale along this edge and the injection button has on its abutting edge
a projection fitting into the recess in the edge of the cap.